A rapid malaria diagnostic test, OptiMAL, was evaluated in a field based study in different epidemiological zones of India. The test can differentiate P. falciparum and non-P. falciparum malaria. The OptiMAL test is based on a dipstick principle for detection of parasite lactate dehydrogenase (pLDH). Since it has been shown that HRP-2 antigen can be detected even after parasitological cure, pLDH detection is more suited for follow up of patients. The sensitivity and specificity of the test compared to microscopy was evaluated in 699 febrile patients from all the study sites. The sensitivity and specificity obtained with the OptiMAL test was 87.9% (79-100%) and 98.9% (95.4-100%) respectively, for diagnosis of falciparum malaria while sensitivity and specificity of OptiMAL for diagnosis of non-falciparum malaria (P. vivax) were 93% (89.2-100%) and 96.8% (94.3-100%), respectively. However, failure to detect high parasitaemia in one patient with P. falciparum malaria is of particular concern. Although the rapid tests have a definite role in diagnosis of malaria especially where expertise for microscopy is not available, the cost of the test kits remains a major obstacle to their wide spread use in developing countries.